In many situations, it is desirable to monitor environmental conditions and/or human or animal activity at a position remote from the observer. This may be because the surveyed region is extensive, so that direct observation of the entire region is impractical. It may be because direct observation would disturb the phenomenon to be observed, for example in the case of observing human or animal behaviour. It may be because the surveyed region is dangerous for direct observation for reasons such as chemical or radiological pollution, seismic or water activity, or the threat of violence from other interested people.
For whatever reason, in these situations, it is required that a sonde may be deployed rapidly and accurately, so that personnel employed in the deployment of the sondes spend as little time as possible in the surveyed location. It is further required that the sonde be autonomous, sensitive to the events of interest and robust enough to require no maintenance after deployment, and have a useful lifetime.
U.S. Pat. No. 6,380,889 describes a reconnaissance sonde carrying sensors and communication equipment. The described sonde is deployed from a rocket, which breaks up to reveal a sonde on a parachute, which descends into the surveyed region. German patent applications DE 4104800 and DE 3313648 and U.S. Pat. No. 3,962,537 all describe surveillance sensors and communication devices, which are launched from a gun, or deployed from a missile.
While such deployment methods may be suitable for the battlefield, they are unsuitable for the purposes of the present invention. The deployment methods described are very long-range. Typically, the sensor will be deployed several kilometers from the launch site. This means that the position of deployment can only approximately be determined before launch. The launch and arrival of the sensor will be very prominent events: the launch being accompanied by the sight and sound of a gun firing or a missile or rocket launching. The arrival of the sensor will be accompanied by the sight of an incoming artillery shell, missile or rocket, breaking up to deploy a parachute carrying the sensor to ground. Such methods are accordingly most unsuitable for situations in which the deployment of sensors is desired to pass relatively unnoticed. Such situations include the monitoring of animal behaviour, or the monitoring of human activity.
The present invention aims to provide a sonde and a method for deploying a sonde, suitable for rapid and accurate short-range ground placement of the sondes. The sonde and the method are suitable for applications such as detection and monitoring of human or animal activity, detection of ground or airborne vehicles, and environmental monitoring. The deployment method and the sonde itself should not be intimidating, to avoid the sonde and the deployment from influencing any activity which is to be monitored. Examples of situations in which human activity may be required to be detected or monitored include crowd control at sports events, political rallies and demonstrations, in disaster relief to detect the presence of survivors, or in monitoring hostile situations.
GB 2386673 describes a target immobilisation device or bolas, which is launched by imparting a spin and a directional velocity to the device or bolas, sufficient to carry it to a target. The device or bolas may carry a radio receiver and loudspeaker. The device or bolas may carry a proximity sensor, imaging sensor or radar device. Images may be formed at a remote location.
FR 2518733 describes a fixed lookout post with vertically ejectable observation platform carrying an infra red detection.
U.S. Pat. No. 6,155,155 discloses a disk shaped anti-mine munition and launcher.
U.S. Pat. No. 6,761,117 discloses a combined reconnaissance sonde and ordinance system in the form of a hand grenade.
GB 1 213 389 discloses a system for launching disk shaped projectiles in a pattern surrounding the launcher.